1. Field of the Invention
The present invention relates to a transmitting apparatus for transmitting an imaged video signal, a receiving apparatus for receiving the video signal by using a plurality of antennas, and a transmitting/receiving system having the transmitting apparatus and the receiving apparatus, and particularly to a transmitting/receiving system for receiving a radio video signal transmitted from a capsule endoscope within a subject by using a plurality of antennas outside the subject.
2. Description of the Related Art
In recent years, in the field of endoscope, there has appeared a swallow type capsule endoscope. This capsule endoscope is provided with an imaging function and a wireless communication function. The capsule endoscope has a function of, after being swallowed from the mouth of a patient for observation (inspection), moving and sequentially imaging inside the body cavity, for example, inside the organs such as stomach and small intestine according to their peristalses before being discharged from a human body.
While moving inside the body cavity, image data imaged inside the human body by the capsule endoscope is sequentially transmitted to the outside via wireless communication, and is accumulated in a memory provided in an external receiving apparatus. A patient brings the receiving apparatus comprising the wireless communication function and the memory function with him/her, and consequently the patient can freely act even in the period after he/she swallowed the capsule endoscope until it is discharged. Thereafter, a doctor or nurse can display the organs' images on a display based on the image data accumulated in the memory, thereby making a diagnosis.
Generally, the receiving apparatus is constituted so that a plurality of antennas for receiving a video signal transmitted from the capsule endoscope are distributed outside the human body and one antenna which is less erroneously receives the video signal is selected and changed for reception. Japanese Patent Application Laid-Open No. 2003-19111 describes a receiving apparatus which performs receiving changeover of a plurality of antennas arranged outside the human body and retrieves the position of the capsule endoscope inside the human body as a video signal originating source based on a field intensity received by each antenna.